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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

GLACIERS OF HAHBIMAN FIORD AND PORT WELLS           339
being at least a century or two old. They end along a straight line but there is no terminal moraine or line of dead tree trunks at the forest edge.
The outer part of the barren zone, farthest from the glacier, is about 100 feet wide and bears scattered trees 65 to 70 years old; while the inner zone, nearest the glacier, has only a very few scattered shrubs none of them more than 20 years old. There is not only a difference in age of trees but a difference in the amount of moss on the rocks in the younger and older parts of the barren zone. Parts of these zones have morainic soil, parts are bare rock and in places there are small stony lateral moraines containing dead wood and rolls of peaty soil.
Growing upon the surface of the largest gravel knob in the outwash fan (b, Fig. 48) is a dense thicket of alders up to 30 years old and some hemlocks, of which the oldest, observed in 1910, was 72 years old. The deposit in this knob is, therefore, correlated with the advance which extended up to the edge of the barren zone, as are also (a) a high level delta in the small valley on the western side of the alluvial fan, and (b) some small mounds of gravel which may represent older outwash. The high level delta which stands about 50 feet above sea level, has a gently-sloping surface and seems to have been built into a small marginal lake at the outer edge of the barren zone. On its surface are trees about 70 years old and it is trenched deeply by the present stream course.
During this period of advance the glacier seems to have had a pronounced bulb shape and to have extended to the fiord; but the second advance evidently did not go nearly so far. Most of the main delta surface is barren, being still occupied by shifting streams, in contrast with (a) the delta at the end of the eastern gorge (d, Fig. 48) on which grow 70 year old conifers, and (b) the delta at the end of the later (western) gorge (c, Fig. 48) on which we saw no alders over 20 years old. In the zone where this later delta coalesces with the present delta of Toboggan Glacier streams there were scattered trees estimated to be a century old, some of them standing dead, some living but in process of being buried and killed by recent gravel deposition. Two or three conifers also grow at sea level on the extreme western edge of the main delta; but none of these appear to be over 60 or 70 years old.
PORT WELLS
General Description. Port Wells (Fig. 49), extending north-northeast from Passage Canal to Pt. Pakenham at the entrance to College Fiord and Barry Arm, is 15 miles long and 6 miles wide. On the western side are Pigot and Bettels Bays, each about three miles long, and four shorter, subordinate bays. The eastern wall is interrupted by two small bays and also by the entrance to Esther Passage, which separates Esther Island from the mainland. A low rock rises above sea level at all stages of tide near the southeastern entrance to Port Wells a mile and a quarter off shore; but with the exception of bars at the entrances to College Fiord and Barry Arm the rest of the fiord is deep. The fiord walls of the mainland rise steeply, but nowhere so precipitously as in upper College Fiord and in Harriman Fiord.
Small Glaciers of Port Wells. The present glaciers of Port Wells are the Bettels and Pigot Glaciers, two moderate-sized ice tongues each terminating a little over a mile from the head of the bay of the same name. There are also a number of much smaller glaciers in the mountains to the west of the entrance to Barry Arm.